STEEL WELDING COMPONENT WITH ALUMINUM OR ALUMINUM ALLOY COATING, AND PREPARATION METHOD THEREFOR

Abstract

A steel welding component with an aluminum or aluminum alloy coating, using a steel welding blank with an aluminum or aluminum alloy coating. The welding blank is composed of a steel substrate (1) and coatings (2, 2); the coating (2) comprises an intermetallic compound alloy layer (21) which contacts the substrate (1), and a metal alloy layer (22) on the intermetallic compound alloy layer (21); on at least one of the coating surfaces of the welding blank, the coating (2) within an area (3) to be welded of the welding blank has been totally removed, and an end face (23) of the coating (2) on the side of the coating within the area (3) to be welded removed has an angle of with a plane vertical to a surface (11) of the substrate (1) which is parallel to the welding seam, wherein is 0-80. Also provided are welding and preparation methods for the steel welding component. The steel welding blank prepared by the method ensures the tensile strength, elongation, and corrosion resistance of a hot-stamped welded joint.

Claims

1. A steel welding blank with an aluminum or aluminum alloy coating, which is composed of a steel substrate and coatings; the coating comprises an intermetallic compound alloy layer in contact with the substrate, and a metal alloy layer on the intermetallic compound alloy layer; wherein, on at least one of coating surfaces of the welding blank, the coating within an area to be welded of the welding blank has been totally removed, and an end face of the coating on the side of the coating within the area to be welded removed has an angle of with a plane vertical to a surface of the substrate which is parallel to a welding seam, wherein is 0-80.

2. The steel welding blank with an aluminum or aluminum alloy coating according to claim 1, wherein the end face of the coating has an angle of =560 with the plane vertical to a surface of the substrate which is parallel to the welding seam.

3. The steel welding blank with an aluminum or aluminum alloy coating according to claim 1, wherein the area to be welded of the welding blank where the coating has been removed has a width selected from the group consisting of 0.4 mm to 1.2 mm, 0.5 mm to 1.0 mm, and 0.6 mm to 0.8 mm.

4. The steel welding blank with an aluminum or aluminum alloy coating according to claim 1, wherein the substrate of the welding blank has a thickness of 0.5 mm to 3 mm.

5. The steel welding blank with an aluminum or aluminum alloy coating according to claim 1, wherein the substrate of the welding blank comprises the following components in weight percentage: (a) 0.08-0.8%, Si: 0.05-1.0%, Mn: 0.1-5%, P<0.3%, S<0.1%, Al<0.3%, Ti<0.5%, B: 0.0005-0.1%, Cr: 0.01-3%, the balance being Fe and unavoidable impurities; (b) C: 0.1-0.6%, Si: 0.07-0.7%, Mn: 0.3-4%, P<0.2%, S<0.08%, Al<0.2%, Ti<0.4%, B: 0.0005-0.08%, Cr: 0.01-2%, the balance being Fe and unavoidable impurities; or (c) C: 0.15-0.5%, Si: 0.1-0.5%, Mn: 0.5-3%, P<0.1%, S<0.05%, Al<0.1%, Ti<0.2%, B: 0.0005-0.08%, Cr: 0.01-1%, the balance being Fe and unavoidable impurities.

6-7. (canceled)

8. The steel welding blank with an aluminum or aluminum alloy coating according to claim 1, wherein the coating of the welding blank is made of pure aluminum or aluminum alloy.

9. A steel welding component with an aluminum or aluminum alloy coating, wherein the steel welding blank with an aluminum or aluminum alloy coating according to claim 1 is tailor-welded by welding in the area to be welded of the welding blank where the coating has been completely removed.

10. A method for manufacturing a steel welding component with an aluminum or aluminum alloy coating, wherein the steel welding blank with an aluminum or aluminum alloy coating according to claim 1 is tailor-welded by welding in the area to be welded of the steel welding blank where the coating has been completely removed to form a welded joint; and obtaining a part by hot press, wherein a cooling rate greater than a critical speed of martensite transformation by quenching in the substrate is selected for cooling.

11. The method for manufacturing a steel welding component with an aluminum or aluminum alloy coating according to claim 10, wherein on at least one of the coating surfaces of the welding blank, the coating within the area to be welded of the welding blank is removed by laser ablation.

12. The method for manufacturing a steel welding component with an aluminum or aluminum alloy coating according to claim 10, wherein on at least one of the coating surfaces of the steel welding blank, the coating within the area to be welded of the steel welding blank is removed by mechanical exfoliation.

13. The method for manufacturing a steel welding component with aluminum or aluminum alloy coating according to claim 10, wherein the welding is a laser welding, preferably a laser welding with filler wire.

14. The steel welding blank with an aluminum or aluminum alloy coating according to claim 2, wherein the area to be welded of the welding blank where the coating has been removed has a width selected from the group consisting of 0.4 mm to 1.2 mm, 0.5 mm to 1.0 mm, and 0.6 mm to 0.8 mm.

15. The steel welding blank with an aluminum or aluminum alloy coating according to claim 2, wherein the substrate of the welding blank has a thickness of 0.5 mm to 3 mm.

16. The steel welding blank with an aluminum or aluminum alloy coating according to claim 14, wherein the substrate of the welding blank has a thickness of 0.5 mm to 3 mm.

17. The steel welding blank with an aluminum or aluminum alloy coating according to claim 2, wherein the substrate of the welding blank comprises the following components in weight percentage: (a) C: 0.08-0.8%, Si: 0.05-1.0%, Mn: 0.1-5%, P<0.3%, S<0.1%, Al<0.3%, Ti<0.5%, B: 0.0005-0.1%, Cr: 0.01-3%, the balance being Fe and unavoidable impurities; (b) C: 0.1-0.6%, Si: 0.07-0.7%, Mn: 0.3-4%, P<0.2%, S<0.08%, Al<0.2%, Ti<0.4%, B: 0.0005-0.08%, Cr: 0.01-2%, the balance being Fe and unavoidable impurities; or (c) C: 0.15-0.5%, Si: 0.1-0.5%, Mn: 0.5-3%, P<0.1%, S<0.05%, Al<0.1%, Ti<0.2%, B: 0.0005-0.08%, Cr: 0.01-1%, the balance being Fe and unavoidable impurities.

18. The steel welding blank with an aluminum or aluminum alloy coating according to claim 3, wherein the substrate of the welding blank comprises the following components in weight percentage: (a) C: 0.08-0.8%, Si: 0.05-1.0%, Mn: 0.1-5%, P<0.3%, S<0.1%, Al<0.3%, Ti<0.5%, B: 0.0005-0.1%, Cr: 0.01-3%, the balance being Fe and unavoidable impurities; (b) C: 0.1-0.6%, Si: 0.07-0.7%, Mn: 0.3-4%, P<0.2%, S<0.08%, Al<0.2%, Ti<0.4%, B: 0.0005-0.08%, Cr: 0.01-2%, the balance being Fe and unavoidable impurities; or (c) C: 0.15-0.5%, Si: 0.1-0.5%, Mn: 0.5-3%, P<0.1%, S<0.05%, Al<0.1%, Ti<0.2%, B: 0.0005-0.08%, Cr: 0.01-1%, the balance being Fe and unavoidable impurities.

19. The steel welding blank with an aluminum or aluminum alloy coating according to claim 4, wherein the substrate of the welding blank comprises the following components in weight percentage: (a) C: 0.08-0.8%, Si: 0.05-1.0%, Mn: 0.1-5%, P<0.3%, S<0.1%, Al<0.3%, Ti<0.5%, B: 0.0005-0.1%, Cr: 0.01-3%, the balance being Fe and unavoidable impurities; (b) C: 0.1-0.6%, Si: 0.07-0.7%, Mn: 0.3-4%, P<0.2%, S<0.08%, Al<0.2%, Ti<0.4%, B: 0.0005-0.08%, Cr: 0.01-2%, the balance being Fe and unavoidable impurities; or (c) C: 0.15-0.5%, Si: 0.1-0.5%, Mn: 0.5-3%, P<0.1%, S<0.05%, Al<0.1%, Ti<0.2%, B: 0.0005-0.08%, Cr: 0.01-1%, the balance being Fe and unavoidable impurities.

20. A steel welding component with an aluminum or aluminum alloy coating, wherein the steel welding blank with an aluminum or aluminum alloy coating according to claim 2 is tailor-welded by welding in the area to be welded of the welding blank where the coating has been completely removed.

21. A steel welding component with an aluminum or aluminum alloy coating, wherein the steel welding blank with an aluminum or aluminum alloy coating according to claim 3 is tailor-welded by welding in the area to be welded of the welding blank where the coating has been completely removed.

22. A steel welding component with an aluminum or aluminum alloy coating, wherein the steel welding blank with an aluminum or aluminum alloy coating according to claim 4 is tailor-welded by welding in the area to be welded of the welding blank where the coating has been completely removed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic view of the steel welding blank with an aluminum or aluminum alloy coating of the present invention after the coating within an area to be welded of the steel welding blank has been totally removed.

[0023] FIG. 2 is a metallographic view of the area to be welded in the steel welding blank of the present invention after completely deplating with a laser beam.

[0024] FIG. 3 is a metallographic view of the area to be welded in the steel welding blank of the present invention after completely deplating with machinery.

[0025] FIG. 4 is a metallographic view of the laser tailor-welded joint after hot press of the present invention.

DETAILED DESCRIPTION

[0026] In order to make the above objects, features and advantages of the present invention more apparent, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments below. The present invention will be understood by those skilled in the art from the spirit indicated in the following embodiments. The technical terms of the present application may be understood broadly based on the spirit of the invention.

[0027] As shown in FIG. 1, the steel welding blank with an aluminum or aluminum alloy coating of the present invention is composed of a steel substrate 1 and coatings 2, 2; the coating 2 (taking coating 2 as an example, the same below) comprises an intermetallic compound alloy layer 21 in contact with the substrate 1, and a metal alloy layer 22 on the intermetallic compound alloy layer 21; on at least one of the coating surfaces of the steel welding blank, the coating 2 within an area 3 to be welded of the welding blank has been totally removed, and an end face 23 of the coating 2 of the welding blank on the side of the coating within the area 3 to be welded removed has an angle of with a plane 100 vertical to a surface 11 of the substrate 1 which is parallel to the welding seam, wherein is 0-80, preferably =560.

[0028] The removal effect of coating 2 can be verified by photomicrography off-line monitoring. The effect of the deplating operation can also be quickly verified by an online optical inspection. The metal alloy layer 22 or the intermetallic compound layer 21 of the coating and the substrate 1 have a significant difference in reflectance to light. Therefore, the deplating operation can be monitored by measuring the reflectance or emissivity by a spectrometer. Specifically, the area where the coating has been removed is illuminated by a light source and directed by an optical sensor; the measured value corresponds to the reflected energy; the values are then compared to the reference values of the reflectivity or emissivity of the alloy layer 22 and the intermetallic compound layer 21 of the coating and the substrate 1 to monitor whether the depth of the deplating operation is up to standard.

[0029] The width W of the area 3 to be welded of the welding blank where the coating has been removed is 0.4 mm to 1.2 mm; preferably 0.5 mm to 1.0 mm or 0.6 mm to 0.8 mm.

[0030] Preferably, the coating 2 of the welding blank is made of pure aluminum or aluminum alloy. Preferably, the substrate 1 of the welding blank has a thickness H of 0.5 mm to 3 mm.

Example 1

[0031] The 1.2 mm steel sheet with an aluminum alloy coating was laser-blanked into a blank of 240 mm110 mm, wherein the composition of the hot dipping solution was: Si: 8.5%, Fe: 2.6%, and the balance was Al and intrinsic impurities. Prior to laser tailor-welding, four different methods for preparing welding blanks were used:

[0032] Method 1 (according to the present invention): Aluminium-silicon coating having a width of 0.6 mm was removed from both sides of the 240 mm length of the blank by laser ablation. =45. A short pulse, high average power laser with a rated power of 850 W, a pulse width of 30 ns and a pulse frequency of 23 kHz was used, and the moving speed of the light spot relative to the steel sheet was 8 m/min. FIG. 2 shows the surface state of the steel sheet after completly deplating.

[0033] Method 2 (according to the present invention): Aluminium-silicon coating having a width of 0.8 mm was removed from both sides of the 240 mm length of the blank by using precision scraping equipment. =45. FIG. 3 shows the edge of the steel sheet after the coating is removed by this method.

[0034] Method 3 (did not according to the present invention): Aluminum alloy layer in the coating having a width of 0.6 mm was removed from both sides of the 240 mm length of the blank by laser ablation, while the intermetallic compound layer was retained.

[0035] Method 4 (did not according to the present invention): Laser tailor-welding is performed directly on the edge to be welded, without any treatment.

[0036] According to the welding process described below, the above blanks were laser tailor-welded. The welding power is 4 kW, the welding speed is 11.75 m/min, the reserved gap of the splice plate is 0 mm, the defocusing amount is 0 mm, and the welded joint after welding has an uncoated-metal region having a width of about 1.0 mm.

[0037] Then, the tailor-welded blank was hot-stamped and quenched at a heating temperature of 930 C., a heating time of 3 minutes, and a pressure holding time of 10 seconds in a water-passing mold. After the above thermal cycle, the tailor-welded blank was completely austenitized. During heating, the atoms in the coating interdiffused with the atoms in the steel, transforming all of the original coating into an intermetallic compound layer havig a thickness greater than that of the original coating. In addition, the intermetallic compound layer has a high melting point and high hardness, preventing the substrate from being oxidized and decarburized during the heating stage and the pressure holding stage. During the pressure holding in the mold, the tailor-welded blank underwent martensite transformation, and finally a welded component having a tensile strength greater than 1450 MPa was obtained.

[0038] Then, the performances of the welded joint were evaluated according to Table 1.

TABLE-US-00001 TABLE 1 Brittle Tensile intermetallic strength Elongation Corrosion compounds inside of the joint of the joint resistance Method the welded joint* (MPa)** (%)** of the joint *** 1 None >1450 >4% Qualified 2 None >1450 >4% Qualified 3 None >1450 4% Qualified 4 Present 1054 1% Unqualified *Electron microscopic analysis of the cross section of the welding seam perpendicular to the welding surface to determine the presence of intermetallic compounds; **The tensile strength and elongation of the joint were tested using a standard tensile specimen with a nominal width of 12.5 mm and an original gauge length of 50 mm; *** Corrosion resistance test was carried out according to DIN50021, DIN50017, DIN50014.

Example 2

[0039] The 1.2 mm steel sheet with an aluminum alloy coating was laser-blanked into a blank of 240 mm110 mm, wherein the composition of the hot dipping solution was: Si: 8.5%, Fe: 2.6%, and the balance was Al and intrinsic impurities.

[0040] Prior to laser tailor-welding, the following method (according to the present invention) was used to remove the coating: Aluminium-silicon coating having a width of 0.6 mm was removed from both sides of the 240 mm length of the blank by laser ablation. A short pulse, high average power laser with a rated power of 850 W, a pulse width of 30 ns and a pulse frequency of 23 kHz was used, and the moving speed of the light spot relative to the steel sheet was 8 m/min. A total of 5 sets of sample blanks were prepared. It should be noted, however, that the angle of each set of blanks (according to the present invention) is different, as shown in Table 2.

[0041] Then, the performances of the welded joint were evaluated according to Table 2.

TABLE-US-00002 TABLE 2 Tensile strength Elongation Corrosion of the joint of the joint resistance Set No. angle (MPa)* (%)* of the joint ** 1 5 1532 5.9 Qualified 2 15 1523 5.7 Qualified 3 30 1507 5.3 Qualified 4 45 1489 4.7 Qualified 5 60 1456 4.2 Qualified *The tensile strength and elongation of the joint were tested using a standard tensile specimen with a nominal width of 12.5 mm and an original gauge length of 50 mm; ** Corrosion resistance test was carried out according to DIN50021, DIN50017, DIN50014.